Who would want access to 1 billion Yahoo accounts?

"If this most recent attack is also state-sponsored, says Albert Gidari, the director of Privacy at the Stanford Center for Internet and Society, "it's government espionage that's really at issue."

Gidari says the size of the breach fits the profile of a government actor, which is typically motivated by an interest in collecting "large volumes of data that gets warehoused for future reference."

"Governments collect because they have voracious appetites for data," Gidari explained. "And they don't have storage limitations, and they're not driven by the economics of commercialism when they act on this stuff. So they may find many uses for it down the road.""